KR20110119583A - Wear-resistant valve for transporting particulate matter and method of making - Google Patents

Abstract

PURPOSE: A wear-resistant valve for transportation of particulate matters and a manufacturing method thereof are provided to reduce the erosion of a valve in a particle collection or transport system caused by contact with the flow of abrasive particles. CONSTITUTION: A wear-resistant valve comprises a valve body(30), a gate housing(45), a gate assembly, and an actuating unit(60). The valve body has an inlet section(35) which is connected to an outlet of a hopper(15) and an outlet section(40). A first channel is defined between the inlet section and the outlet section. The gate housing comprises an entrance part(50) which is connected to the outlet section of the valve body and an exit part(55) which is connected to a transport line. The gate assembly has opening and closing positions and includes a gate and an annular seat. The actuating unit reversibly transfers the gate assembly between the opening and closing positions.

Description

Wear-resistant valve for transporting particulate matter and its manufacturing method {WEAR-RESISTANT VALVE FOR TRANSPORTING PARTICULATE MATTER AND METHOD OF MAKING}

The present invention relates to a valve used for the transport of particulate matter. In particular, the present invention relates to methods of making wear resistant valves for controlling the flow of "dry" particles or particulate matter in pneumatic collection or transportation systems and the use of such valves.

Among other industries, various industries, such as compounding and plastics processing, chemical and mineral processing, food industry, and pharmaceutical industry, include one place from another to remove particulate by-products and waste formed during the manufacturing process or from other places. It requires the transport of small particulate matter into the furnace. Combustion of coal or similar fuels represents one example process of producing small by-products or waste particles (eg, fly ash, commonly known) that can be removed from the combustion site as part of the exhaust gas. The diameters of the small particles flowing in the particulate collection or delivery system range from about several millimeters to about 0.01 μm. One of the common features for most particle collection or delivery systems is that the particles should not be vented to the atmosphere as emissions will cause complex environmental issues. Thus, various techniques, such as electrostatic precipitators and bag filters, have generally been used to remove small particles from the exhaust gas before it is released to the atmosphere.

Small particulate matter, typically transported through a delivery system, has been collected in one or more hoppers or bins. Transfer of the particles from the bin (s) or hopper (s) to a desired location, such as a compounding vessel or disposal unit, can be accomplished using a particle collection or delivery system. Such particle collection or delivery systems generate pressure differentials through the use of compressed air and / or vacuum to allow small particles to flow from the hopper to the desired location through control valves and transfer lines. Although this process may appear to be a natural simple process, the movement of small particles may cause serious problems associated with the erosive wear of devices and equipment exposed to the flow of the particles.

Particle collection or delivery systems basically move large quantities of small relative abrasive particles in a pressure / vacuum line or transfer operation that can cause a high differential pressure gradient. This high differential pressure change causes small particles to flow through the narrow gap provided in the control valve, eroding the valve assembly, reducing the valve's efficiency, and shortening the valve's useful life. This problem is evident in the valve used for the lateral loading of the main pressure / vacuum line. In this case, a lateral-style valve must rotate the abrasive particles at an angle of about 90 degrees as they flow from the hopper into the main pressure / vacuum line.

The abrasive particles can cause erosion of multiple parts in a side-style valve comprising a body, a gate, and a seat. Such erosion can occur in a very short time, such as weeks. Ultimately, erosion wear on valve components leads to reduced system capacity or excess down-time leading to repairs, all leading to loss of productivity. Therefore, there is a problem in maintaining the efficiency of the valve assembly when the valve assembly operates in a polishing environment. Thus, there has been a continuing need to improve side-style valves so that systems using the valves exhibit reduced erosion wear and provide high reliability and lower maintenance.

The present invention provides a side-style valve for controlling the flow of abrasive particles along a predetermined path from the outlet of the hopper to the transfer line in a particle collection or delivery system. The valve reduces the occurrence of erosion wear caused by contact with the flow of abrasive particles. Such a reduction in wear is achieved by placing the seat of the valve's closing mechanism such that ash particles are non-concentric and / or oversized with respect to the outlet of the valve body flowing therethrough. The location of the sheet partially hides the sheet from a predetermined path through which abrasive particles flow, reducing the erosion wear caused by the sheet. In addition, the inner wall of the valve has an angle at which the collision angle of incidence with the flow of abrasive particles is relatively small, thereby reducing the damage occurring during the collision. Finally, the width and length of the outlet orifice in the valve body are pre-determined to reduce the speed of the abrasive particles and to reduce the area where particles are accelerated as they flow through the valve. The decrease in the speed of the abrasive particles slows down the wear rate of the parts in the valve.

According to another aspect of the present application, there is provided a method of manufacturing a valve body and a gate housing comprising two wear parts in a valve to further improve the wear resistance of the valve. In particular, the method increased the formation of metal carbides in high wear zones to reduce erosion in these areas by the flow of abrasive particles. This method involves the use of localized chilling of the core in the mold used in the metal casting process. Valves of the structure according to the design and method of the present application have been found to exhibit superior wear resistance as compared to conventional valves.

Further applicable areas will be apparent from the description set forth herein. The description and specific examples described herein are for purposes of illustration and are not intended to limit the invention.

1 is a perspective view of a fly ash conveying system made in accordance with the teachings herein;
2 is a perspective view of the valve assembly of FIG.
3 is a perspective view of a valve assembly made in accordance with the teachings herein wherein the valve is disconnected from the fly ash delivery system.
4 is a cross-sectional view of the valve body and gate housing in the valve assembly of FIG.
5A is a cross-sectional view of the valve body and gate housing in the valve assembly of FIG. 3 shown in different perspective.
Fig. 5B is a cross sectional view of a conventional valve body and gate housing showing the confinement of the throat length L _t .
FIG. 6 is a view schematically showing the arrangement between the orifice of the first passage in the outlet portion of the valve body and the inner face of the oversized annular seat, where (A) is the first passage of the annular seat; FIG. Of the orifice of the first passage and (C) the non-circular of the orifice and the annular sheet of the first passage It is a geometric shape of.
FIG. 7 is a cross-sectional view of the valve body and gate housing of the valve assembly of FIG. 3, wherein a wear insert forming part of the inner wall of the trot area is integrally formed with (A) the access cover, and (B) It is formed integrally with the separating piece disposed and maintained by.
8 is a view schematically showing a method of manufacturing a valve according to another embodiment of the present application.
9 graphically illustrates normalized erosion of conventional valves shown as a function of particle impact angle and valves made according to the method of FIG.

The following description is, in fact, described by way of example only and is not intended to limit the disclosure to the description or application or use thereof. For example, the flow of fly ash particles through the valves and the use of the valves in the fly ash delivery system have been described as illustrative of this application, among other things plastic composition, chemical and mineral processing, food preparation and packaging, cement mixing, and pharmaceuticals. The use of valves for controlling the flow of abrasive particles and abrasive particles of different types in particle transport systems used in a variety of different industries such as preparation is contemplated within the scope of this application. Abrasive particles flowing through such valves include, but are not limited to fly ash, concrete / cement, aluminum oxide, calcium carbide, ceramic dust, clay, flour, foundry sand, magnesium oxide, metal salts, silica, soda ash, talc, titanium dioxide , And zinc oxide. Corresponding reference numerals described throughout the specification and drawings refer to similar or corresponding parts and features.

The present application provides a valve for controlling the flow of abrasive particles (eg ash, etc.) along a predetermined path from the outlet of the hopper to the transfer line in a particle (eg fly ash) collection or delivery system. Referring to Figures 1 and 2, the fly ash delivery system 10 according to the present application includes at least one hopper 15 having an outlet 20 engaged to the valve assembly. Each valve assembly 25 is additionally connected to a transfer line 27 or pipeline used to deliver ash particles to the processing unit. The valve is designed to reduce the occurrence of erosion wear caused by contact with the flow of ash particles. The transfer line includes multiple connectors, such as a T-type or Y-type connector, used to connect the valve assembly 25 to a single transfer line 27.

Referring to Figure 2, the outlet of the hopper 20 is formed in the size necessary for the connecting pipe to connect the outlet 20 to the valve assembly 25. As shown in FIGS. 2 and 3, the valve assembly 25 generally includes a valve body 30 connected to the outlet 20 of the hopper 15 and a gate housing 45 connected to the transfer line 27. do. The valve body 30 and the gate housing 45 are also connected together. The valve body 30 includes both an inlet section 35 and an outlet section 40. Similarly, the gate housing 45 also includes an inlet 50 and an outlet 55. The valve assembly 25 further comprises actuating means 60 for moving the valve between the open and closed positions.

2 to 5, the inlet section 35 and the outlet section 40 of the valve body 30 are perpendicular to each other and have a first passage 65 through which abrasive particles can flow. It is limited. The outlet section 40 further defines a centerline of the outlet section from which abrasive particles are discharged from the first passage 65. The inlet section 35 is adapted to be connected to the outlet 20 of the hopper 15 as shown in FIG. 2. An angle α of at least 90 degrees is established between the centerline of the orifice established by the inlet section 35 (centerline of the inlet section) and the centerline of the orifice established by the outlet section 40 (centerline of the outlet section). The first passageway 65 has an inner surface 70 that is curved. The valve body 30 also includes a removable access cover 75 (shown in FIGS. 4 and 5). The access cover 75 has an interior surface that is curved to be generally similar or identical to the interior surface 70 of the valve body 30 defining the first passage 65.

The inlet 50 and the outlet 55 of the gate housing 45 are parallel to each other and define a second passage through which abrasive particles can flow. The outlet 55 of the gate housing 45 is connected to the transfer line 27. The second passage 80 is additionally defined by the inner wall 85 of the gate housing 45 at the lower part of the passage, with an angle β of the inlet 50 at the plane of the inner wall 85. The outlet 55 is inclined to be established between the plane of the inner wall 85. The inner wall 85 at the inlet 50 with its lower portion cylindrical is parallel to the centerline of the inlet 50. The angle β is also limited to the angle established between the line along the surface of the inner wall 85 at the outlet 55 and the centerline (inlet centerline) of the inlet 50. An angle β of about 15 degrees is preferred.

Referring to FIG. 5A, the inner wall 85 of the second passage 80 in the gate housing 45 also has an inner wall 85 generated between the inlet 50 and the outlet 55. It is described as having a total length L _y , with a slope. In addition, the inlet 50 is defined to have a predetermined length L _x , the length of which is inclined at the inner wall and the annular sheet () at the outlet 55 of the gate housing 45. It is the length of the cylindrical inner wall 85 at the inlet 50 situated between 105. The length L _x is in a range according to the relationship represented by the following expression (1).

0.2 (L _y ) ≤ L _x ≤ 0.7 (L _y ) Equation 1

4 and 5A, the gate assembly 95 is disposed near the inlet portion 50 of the gate housing 35 having an open position and a closed position. The gate assembly 95 includes a gate 100 sized to occlude the second passage 80 and the stationary annular sheet 105. The annular sheet 105 comes into contact with and engages with the surface of the gate 100. Gate assembly 95 is considered closed when gate 100 contacts and engages sheet 105 around its perimeter. The gate assembly 95 is considered open unless the gate 100 is in full contact with the perimeter of the sheet 105. In addition, the gate assembly 95 includes a gate arm 107, which arm moves the gate 100 so that the gate assembly 95 can reversibly transition between its open and closed positions. Communication means 60, which is best shown in FIG. The actuator 60 is preferably designed such that parts comprising the actuator can be mounted on both sides of the valve to fit the desired space.

The valve 25 is optimally adapted to reduce the incidence of erosion wear caused by contact with the flow of abrasive particles. In particular, the seat 105 as shown in FIGS. 4 and 5A is non-concentrically disposed and / or oversized with respect to the outlet section 40 of the valve body 30 so that its surface is re-grained. Is at least partially concealed from a predetermined path through which flow reduces erosion caused by the sheet 105 and maintains the performance of the sheet 105 to form a leak-free seal in the gate 100. . In addition, the angle α defining the inner surface 70 of the first passage 65 and the angle β defining the inner wall 85 of the second passage 80 are caused by erosion wear caused by the flow abrasive particles. Is determined in advance to reduce. As shown in FIG. 4, the trajectory of the particles is predicted to impinge or contact the inner surface 70 of the outlet section 40 of the valve body 30 and the surface of the inner wall 85 of the gate housing 45. .

The valve 25 made in accordance with the teachings of the present application addresses many of the deficiencies and problems associated with conventional valves when the main pressure / vacuum line is used for side loads in a fly ash delivery system. In general, conventional valves used in this manner suffer from excessive erosion caused by the impact of ash particles in many places. The valve additionally includes a throat area near the outlet of the valve body which can cause a high velocity of the flow of ash particles and acts on the acceleration zone. As shown in Fig. 5B, the trot region is defined by a length L _t representing the length of the smallest diameter region that extends through the outlet of the valve body, which can extend to the gate. The inner face of this outlet trot area is one of the major areas of the valve that are subject to severe wear due to the impact of abrasive ash particles. The amount of wear occurring on the inner face of the outlet trot can be reduced by using an optional wear resistant insert. However, such inserts, which are generally made of tungsten carbide or ceramic materials, are expensive options.

As shown in FIGS. 4 and 5A, the valve body 30 made in accordance with the teachings herein reduces the velocity of ash particles and reduces the size of the acceleration zones, resulting in wear caused by the inner surface of the trot region 90. Is reduced. This fact is realized by defining the cross sectional width W _tv and the length L _t of the trot region 90 by the relation provided by Eq. The width W _tv of the trot region 90 greater than about 3.75 inches (ie, the speed limit of ash particles) and the length L _t of the trot region less than about 1 inch (ie, the limit of the acceleration zone) are preferred. .

0 ≤ L _t ≤ 0.3 (W _tv ) Equation 2

The annular seat that the closing mechanism seals against is another area in conventional valves where wear may occur due to collisions with the flow of ash particles. In conventional valves the seat generally coincides with the inner face of the valve. This location allows the sheet to be exposed to allow collision and erosion by the flow of ash particles.

Gate housing 45 made in accordance with the teachings herein, as shown in FIGS. 4 and 5A, reduces wear caused by the annular sheet 105. Reduced wear of the annular seat 105 improves the performance of the seat 105 to form a leak-free seal in the gate 100, extending the overall life time of the valve. Referring to Figures 6A and 6B, the reduction in wear caused by the annular sheet 105 extends the width W _{sv of the} orifice defined by the inner surface of the annular sheet 105, and the sheet 105 is achieved by placing concentrically (FIG. 6A) or non-concentrically (FIG. 6B) the orifice of trot region 90 in outlet section 40 of valve body 30. FIG. In each case, the lower portion of the surface of the seat 105 is disposed below the inner face 70 of the valve body 30 at a predetermined distance D _s to conceal the seat from the flow path of the ash particles. do. In other words, the width W _tv of the orifice in the trot area is smaller than the width W _sv of the orifice defining the inner face of the annular sheet 105. The predetermined distance D _s between the inner face 70 of the valve body 30 and the lower face of the seat 105 is in the range according to the relationship represented by equation (3). Preferably, the distance D _s is greater than about 400 mils (0.4 "), and is preferably about 500 mils (0.5") in many applications.

0 <D _s ≤ 0.25 (W _tv ) Equation 3

Those skilled in the art will appreciate that the orifices of the trot region 90 or the orifices of the annular sheet 105 may deviate from the circular geometry without exceeding the scope of the present specification. In other words, the orifice of the trot region 90 or the orifice of the annular sheet 105 may take on a non-circular geometry, including oval, polygonal, or combinations thereof, without limitation. For example, FIG. 6C shows an example in which the orifice of the trot region 90 has an elliptical shape. Typically, non-circular shapes will have widths in both horizontal and vertical dimensions. As shown in FIG. 6C, the elliptical trot area 90 is provided with the shown vertical width dimension W _tv and horizontal width dimension W _th . In Fig. 6C, since the annular sheet 105 is circular, the dimensions of the vertical width W _sv and the horizontal width (not shown) are the same. One skilled in the art will understand that the dimensions of the vertical width of the trot area W _tv and the annular sheet W _sv are used to determine the distance D _s . Also, those skilled in the art refer to the sheet 105 in which the annular sheet 105 for the non-circular orifice forms a ring around the circumference of the orifice, and the gate 100 of the gate assembly 95 is It will be appreciated that it includes the face that engages in contact with the sheet 105.

The oversize width of the sheet orifice W _sv and the non-concentric arrangement of the sheet 105 allows ash particles to overshoot the sheet 105, avoiding collisions, and reducing erosion of the sheet 105. Let's do it. Concealment of the seat 105 in this manner generally allows wear to occur on the inner face of the valve body 30 before it affects the life of the annular seat 105. For example, if the distance D _s between the inner face 70 of the valve body 30 and the surface of the seat 105 is 500 mils, then the inner face 70 of the valve body 30 will generally have a seat ( Prior to erosion of 105, the valve assembly 25 may be eroded by 500 mils during operation. In this example, the increased life of the valve body 25 is expected to operate about 2500 hours in extreme erosion conditions, which is equivalent to a typical service life of about 7 years. The 2500 hour increased life time was determined by dividing the distance (D _s ) (eg 500 mils) by an average erosion rate of 0.2 mils per hour measured after operating the valve under extreme erosion conditions in a fly ash delivery system.

Finally, in conventional valves the inner face of the valve before and after the closing mechanism is generally either side in the plane of the same geometry, or the inner face behind the closing mechanism is slightly inclined or raised above the inner face of the valve prior to the closing mechanism. . Thus, the inner face of a conventional valve placed immediately behind the closing mechanism is another area that will be subjected to multiple collisions with fluid particles that cause severe erosion wear.

4 and 5, the gate housing 45 made in accordance with the teachings of the present application reduces wear caused by the inner wall 85 disposed behind the gate assembly 95 from the impact of ash particles. This is achieved by designing the gate housing 45 such that ash particles overshoot the starting portion of the inner wall 85 and collide with the inclined portion of the inner wall 85 between the angle β and the outlet 55. It became. The erosion damage caused by the impact of ash particles was reduced due to the low impact angle caused by these sloped surfaces.

Referring to Figures 7A and 7B, the lower inner face 70 of the trot region 90 of the outlet section 40 of the valve body 30 and the interior of the outlet 55 of the gate housing 45 The height difference H _Δ is defined between the bottom surface of the wall. This height difference H _Δ lowers the surface of the seat 105 at a predetermined distance D _s under the inner face 70 of the valve body 30 (ie, conceals the seat from the flow path of abrasive particles), And inclining the inner wall of the outlet portion 55 of the gate housing 95 (i.e., reducing the angle of collision with the abrasive particles), thereby reducing the wear incidence in the valve 25. The height difference H _Δ follows the relationship provided by Equation 4, where W _o is the opening at the outlet adapter 165 used to connect the outlet 55 of the gate housing 45 to the transfer line 27. Indicates the width of.

0 <H _△ ≤ 0.5 (W _o ) Equation 4

The value of height difference _(△ H) is determined in advance that there is a relationship between _△ H and D _s. This relationship between the height difference H _Δ is optimized such that the life expectancy of the sheet 105 and the inner wall of the gate housing 85 is approximately equal. Preferably, the relationship between H _Δ and D _s follows the relationship provided in equation (5).

식5

Equation 5

In addition to erosion wear, conventional valves also suffer from reduced efficiency due to undesirable accumulation of ash particles in the valve. The inner face of a conventional valve changes direction through an angle of 90 degrees or less between the inlet and outlet of the valve. The end result of this acute angle results in an accumulation space that results in a reduced or limited flow level, where ash particles are collected and compacted. Accumulation of ash particles in such spaces leads to loss of productivity due to downtime associated with the need for periodic maintenance to remove compacted or accumulated ash deposits from the valve.

As shown in FIGS. 4 and 5, the valve body 30 made in accordance with the teachings herein reduces the amount of ash particles collected and compacted in the valve body 30. This has been done by allowing the inner face of the valve body 30 to be curved at an angle α of at least 90 degrees. The angle α is defined as the intersection between the centerline of the orifice established by the inlet section 35 and the centerline of the orifice established by the outlet section 40 of the valve body 30. The inner surface 70 of the generated curve of the valve body 30 is streamlined to reduce the occurrence of particle packing, thereby providing access to the second channel through the clean-out port of the access cover 75. Keep it to the minimum.

According to one aspect of the present disclosure, the inlet section 35 of the valve body 30 has an orifice having a diameter in the range of about 8 to 12 inches. The outlet 55 of the gate housing 45 has an orifice having a diameter in the range of about 4 to 6 inches and includes the use of the necessary adapter 165 as shown in FIG. The inlet section 35 of the valve body 30 and the outlet 55 of the gate housing 45 are similar to the outlet 20 of the hopper 15 having a similar diameter of about 8 to 12 inches, and similar to 4 to 6 inches. It is connected to a conveying line 27 or pipeline of diameter. The change of the flow direction in the valve body defined by the angle α helps to regulate the flow of ash and to prevent the overflow of the conveying line 27.

According to another aspect of the present disclosure, the access cover 75 optionally includes a wear insert 155 (FIG. 7A) formed integrally with a part of the access cover 75 or a wear insert 160 constituting a separate part ( 7B). The wear inserts 155 and 160 are used as sacrificial parts where abrasive particles collide and wear out while the valve is operating. In this regard, the wear inserts 155, 160 become part of the inner face 70 of the trot region 90 of the valve body 30. If wear occurs in the trot area 90, the wear inserts 155, 160 are replaced with other wear inserts 155, 160. Additionally, the access cover 75 includes a hinged face 150 such that the access cover 75 pivots the wear insert 155 to a portion of the interior face 70 of the trot area 90. Make it possible. If the wear insert 160 is a separate component, the insert 160 is held in place as part of the inner face 70 of the trot region 90 by any means known to those skilled in the art. A fixed, non-limiting substrate includes a positioning portion of the access cover 75, a groove and tongue structure, a wedge joint, and a stop disposed around the outlet section 40. . According to another aspect of the present disclosure, the valve 25 is a movable gate mounted to the gate housing 45 including the gate 100 to ensure proper alignment of the gates 100 to the seat 105 and active sealing operation. It is designed as an assembly 95. The gate assembly 95 is a type of gate known to those of skill in the art and for a column of at least about 20 feet of accumulated ash in the hopper 15 in addition to the pressure difference used to transfer the ash to a non-limiting substrate. A sealable flapper style gate assembly. The gate assembly 95 is made of stainless steel, tungsten carbide or other metals or alloys used in industry. The surface of the gate 100 optionally includes a wear resistant coating such as ionic nitride material, ceramic material, or tungsten carbide, among others. The gate 100 is operated to move between its open and closed positions using any type of actuation means 60 and includes a pneumatic air cylinder as a non-limiting substrate. In the case of pneumatic failure, the check valve of the supply line can maintain the air pressure necessary to provide a tight seal between the gate 100 and the seat 105.

The valve body 30 is connected to the outlet 20 of the hopper 15 and to the gate housing 45 by any type of coupling known to those skilled in the art, including but not limited to universal bolt-flange designs. The gate housing 45 is connected to the valve body 30 and the transfer line 27. Each of the couplings is preferably designed to allow easy assembly and disassembly of the valve 25 from the fly ash delivery system 10. For example, the connection between the gate housing 45 and the valve body 30 may be such that the valve body 30 provides for maintenance of the gate assembly 95 including the annular seat 105. Enable disconnect from

According to another embodiment of the present application, there is provided a particle collector such as an electrostatic precipitator, bag house, or economizer, and a particle delivery system 10 for collecting and controlling flowing abrasive particles between a processing unit or a compounding vessel. For example, fly ash delivery system 10 generally includes at least one hopper 15 having an inlet (not shown) and outlet 20; At least one transfer line 27; A design and manufacture valve 15 in accordance with the above-described parameters; And pressure or vacuum sources. Whereas the inlet of the hopper 15 is in communication with the ash collector to receive the fly ash particles, the transfer line 27 is in communication with the processing unit for delivery of the ash particles. The valve 25 has a gate housing 45 and a valve body 30 to control the flow of ash particles between the hopper 15 and the transfer line 27. The valve body 30 is connected to the outlet of the hopper 15. Similarly, the gate housing 45 is connected to the transfer line 27. Pressure and / or vacuum sources cause ash particles to flow from the ash collector to the processing unit.

Another object of the present invention is to provide a method of manufacturing a valve for controlling the flow ash particles in a fly ash collection or delivery system. The valve 25 used in this fly ash delivery system 10 is the valve 25 described above with the valve body 30, the gate housing 45, and the gate assembly 95 for opening and closing the valve 25. The valve body 30 and the gate housing 45 are optimized to reduce the incidence of erosion wear caused by contacting fluid particles between the hopper 15 and the transfer line 27 in the delivery system 10.

Referring to Figure 8, this method 200 generally includes multiple steps, the first of which comprises a first mold 205 of a valve body comprising an outer shell, a cavity, and an inner core. To provide. The cavity of the first mold is then filled 210 with molten or liquid metal. The inner core of the first mold is designed to cool the molten metal in a section of the mold that represents the inner face of the trot region of the valve body that allows cooling faster than the remaining molten metal in the cavity. Thus, the molten metal in the inner core is cooled 215 and the casting of the valve body is removed 220 from the mold.

Then, the above steps are repeated for the formation of the gate housing. The steps generally include a step 225 of providing a second mold of a gate housing having an outer cell, a cavity, and an inner core. The cavity of the second mold is then filled 230 with molten metal. The inner core of the second mold is designed to cool the molten metal in a section of the mold showing the lower wall including the inclined inner wall of the gate housing that allows for cooling faster than the remaining molten metal in the cavity. Molten metal in the inner core of the mold is cooled (235) and the casting of the gate housing is removed from the second mold (240).

The method 200 further includes providing 245 a gate having an open position and a closed position, and providing an actuator 250. The method 200 further includes assembling 255 the valve body, gate housing, gate assembly, and actuator to form a valve.

Solidification of the molten metal in the method 200 described above occurs through a combination of nucleation and crystal growth. The core used in the method 200 is designed to act as a heat sink capable of cooling the molten metal. The fast cooling rate of the molten metal near the core promotes the formation and growth of hard metal carbide grains. Accordingly, metal carbide grains are formed in the trot region 90 of the valve body 30 as part of the inner face 70 and as part of the lower inner wall 85 of the gate housing 45. These metal carbides are embedded in a metal matrix having a different microstructure than the carbides. Such metal matrices exhibit hardness that is about 3 to 5 times softer than carbide grains. The hard metal carbide grains are generally the same size as the ash particles. The size and volume fraction of the metal carbide grains formed during the cooling steps 215 and 235 have the property that they are more likely to impact the harder carbide grains than the softly enclosed matrix. Thus, the presence of these hard metal carbides can reduce the incidence of erosion wear resulting from contacting or colliding with ash particles.

Cooling steps 215 and 235 are carried out in a localized area which is severely abraded in the valve body 30. The cooling steps 215 and 235 are necessary because the ductility of the limited material design for the valve 25 is required to remain in the casting sufficient enough to enable this when secondary machining is desired or desired. Local area. The local cooling zone selectively processes the valve body 30 and / or other areas of the gate housing 45 while curing the areas of the valve body 30 and the gate housing 45 that are susceptible to severe erosion wear. Makes this possible.

Preferably, the molten or liquid metal used in the method 200 of manufacturing the valve is iron. Thus, the carbide formed during the cooling steps 215 and 235 will be iron carbide. However, a small predetermined amount of chromium metal is included in the molten iron used during the filling step 205 for the valve body. In addition, chromium may be included in the molten metal used to form the gate housing 35 as needed. Chromium will be included in the carbide formed during the cooling steps 215 and 235 which generate a very hard carbide phase. . By the way, the addition of chromium to the molten iron will harden not only the area to be cooled but to a certain extent of the rest of the casting, so that the addition of chromium is preferably done only for the casting of the valve body 30 which is very susceptible to erosion. The addition of chromium of the molten metal used to form the gate housing 45 is done so that the increase in hardness does not suppress the need for complicated machining to complete the manufacture of the gate housing 45.

Measurement of the hardness indicated by the valve body 30 and / or the gate housing 45 may be used to predict wear resistance. In general, wear resistance will increase as the hardness of the material received in the polishing environment increases. Such hardness measurements are performed at various locations in the valve body 30 and / or gate housing 45 to determine the change in hardness caused by the addition of a small amount of chromium from the formation of iron carbide or to the ferrous metal.

Similar process steps may be used to prepare the wear inserts 155, 160 used in the valve body 30 as a separate part or as part of the access lid 75 without exceeding the scope of the present disclosure. In this case, the hardness of the wear inserts 155, 160 is used to provide the wear resistance necessary to extend the life of the valve body 30. If the wear inserts 155 and 160 are badly worn, the inserts 155 and 160 are replaced with new inserts 155 and 160 to further extend the life of the valve.

Those skilled in the art will appreciate that Brinell hardness tests (eg, ASTM E10-08 entitled "Standard Test Methods for Brinell Hardness of Metallic Materials") are used to determine the hardness of cast iron. Such tests generally involve colliding an indenter with the casting and subsequently measuring the size of the resulting indentation. The smaller the size of the indentation, the greater the hardness of the casting. Castings associated with conventional valves were measured to be in the range of about 100 to 200 brinelles. In addition, the valve body 30 and the gate housing 45 prepared according to the method 200 herein were tested. The hardness of the inner surface 70 in the trot region 90 of the valve body 30 subjected to the cooling 215, 235 processing steps and in the inclined inner wall 85 of the gate housing 45 is about 400 to 500 It was measured to be Brinell. Other portions of the valve body 30 and gate housing 45 that have not been exposed to the cooling 215 and 235 process will exhibit hardness similar to cast iron or steel used in conventional valves. This 2x-3x increase in hardness resulting from the cooling (215, 235) processing steps is due to the internal surface at the trot region 90 of the valve body 30 and at the inclined inner wall 85 of the gate housing 45. 70), leading to a general increase in wear resistance.

The following examples are set forth to illustrate the invention and do not limit the scope of the invention. One skilled in the art will understand that erosion (E) is a function of the angle at which the particles collide with the material, the speed at which the particles travel, and the surface hardness of the material with which the particles collide. In addition, erosion is substantially relational expression: E α v are known for measuring the speed (v) of the collision of the particles ^{2 0.5.} Prediction models for erosion caused by the impact of small particles can be derived and used to provide a normal erosion damage curve that eliminates the dependency on velocity. Details for deriving a normal erosion damage curve using the example model described above are described by YI Oka, H. Onogi, T. Hosokawa, and M. Matsumura, which are incorporated herein by reference and refer to "Solid Particle Collision." Dependency of collision angle of erosion damage caused by "Heading, Wear, vol. 203-204 (1997), pp. 573-579. Additional techniques of example models are described by Orca et al., The contents of which are incorporated herein by reference. 259 (2005), pp. 95-101 and Wear, vol. 259 (2005), pp. 102-109.

Erosion damage curves are determined using an example model such as Orca for conventional valves and valves 25 as shown in FIGS. 4 and 5 manufactured according to the method 200 as disclosed in FIG. It became. The erosion curves as shown in Figure 9 represent values for normal erosion of the inner face of the valve whose surface is shown as a function of the angle at which fly ash particles collide. Normal erosion is defined as the actual erosion caused by the material under the angle of incidence or impact during normal operation of the valve divided by the erosion that occurs when the angle of incidence or impact is 90 degrees and the impact velocity is the same.

As shown in Figure 9, the expected normal erosion of a conventional valve is greater than the normal erosion of the valve 25 prepared according to the present invention at an impact angle that is greater than zero and less than about 75 degrees. If a locally harder metal material is assumed to have greater resistance to 90 degree collisions of the flowing particles, these erosion curves indicate that the valve 25 of the present application exhibits greater wear resistance than conventional valves. For example, the erosion of the gate housing in a conventional valve with a conventional hardness in which fly ash collides at an angle of 20 degrees may result in the same hardness exposed to the impact of fly ash particles at a 90 degree angle (see point A in FIG. 9). It will erode 30% higher than cotton. In contrast, the gate housing of the valve prepared according to the teachings herein with the material hardness generated according to the method 200 is at an angle of 90 degrees due to the very low impact angle established by the inclined inner wall 85 (FIG. See point B at 9) It will erode at a rate of 80% lower than similar surfaces exposed to the impact of fly ash particles. For further explanation, assuming that the erosion resulting from the impact of fly ash at an angle of 90 degrees is 20% lower than the surface prepared according to method 200 than for surfaces in conventional valves, the teachings herein (eg, The gate housing of the valve prepared according to FIG. 2) will exhibit corrosion resistance of conventional valves greater than eight times (8x) (e.g., compared to point B for point A in FIG. 9).

Those skilled in the art will recognize that the described measurements are standard measurements that can be obtained by a variety of different test methods. The test methods described herein represent only one available method of obtaining each required measurement.

The foregoing descriptions of various embodiments of the present invention have been described for purposes of illustration. Accordingly, the described embodiments are not intended to limit the invention. Many modifications or variations are possible in light of the above teaching. The above-described embodiments are selected and described in order to give the best explanation for the basic principles of the present invention and its practical application, and those skilled in the art can make various modifications in various embodiments to suit the particular use contemplated. Will be able to utilize Accordingly, all changes and modifications made within the scope of the present invention are included in the present invention, and the present invention is limited by the appended claims.

Claims (30)

A valve for controlling the flow of abrasive particles along a predetermined path from the outlet of the hopper to the transfer line in a particle collection or delivery system, the valve comprising:
Having an inlet section and an outlet section, the inlet section is formed to be connected to the outlet of the hopper, the inlet section and outlet section defining a first passage between the inlet section and the outlet section through which abrasive particles can flow. A body;
A gate housing having an inlet connected to an outlet section of the valve body and an outlet connected to a transfer line, the gate housing defining a second passage between the inlet and outlet through which abrasive particles flow;
A gate assembly having an open position and a closed position, the gate assembly having a gate sized to close the second passage and an annular sheet disposed near the inlet of the gate housing and in contact with and engaged with the gate; And
An actuating means for reversibly moving the gate assembly between an open position and a closed position;
The annular sheet is disposed in size with respect to the outlet section of the valve body such that a portion of its inner face is at least partially concealed from the flow of abrasive particles when the gate assembly is in the open position, the gate assembly being disposed of And the gate is in its closed position when the gate contacts the seat so that flow is blocked. The orifice of claim 1, wherein the first passage further defines an orifice in an outlet section of the valve body having an outlet section centerline and an orifice in an inlet section of the valve body having an inlet section centerline; And wherein the first passageway of the valve body is further defined by an interior surface that is curved such that an angle α of at least 90 degrees is established between the inlet section centerline and the outlet section centerline. 3. The valve of claim 2, wherein the valve further comprises an access cover having an interior surface that is curved to be generally the same as the interior surface of the valve body defining the first passageway. 2. A valve as claimed in claim 1, wherein said actuating means is a pneumatic actuator, said actuator being designed to be mountable on either side of the valve such that the component comprising the actuator is reversible. The outlet section of the valve body further comprises a trot region having an interior surface defining an orifice with a cross sectional width (W _tv ) and a length (L _t );
And the length L _t is in the relation: 0 ≦ L _t ≦ 0.3 (W _tv ). 6. The valve of claim 5, wherein the trot area has a cross-sectional width (W _tv ) greater than about 3.75 inches and a length (L _t ) less than about 1 inch. 2. The method of claim 1, wherein the second passage further defines an orifice at an inlet of the gate housing having an inlet centerline; And the second passage of the gate housing is further defined by an inclined inner wall such that the angle [beta] is established by measuring between a line parallel to the inner wall and the inlet centerline. 8. The method of claim 7, wherein the angle β is established at the inner wall at the interface between the inlet and outlet; The inner wall has a total length (L _y ) and the inlet has a predetermined length (L _x ), the length of L _x is within the relationship: 0.2 (L _y ) ≤ L _x ≤ 0.7 (L _y ) Characterized by a valve. 8. The valve of claim 7, wherein said angle [beta] is about 15 degrees. 2. The method of claim 1, wherein the second passage further defines an orifice at an inlet of the gate housing having an inlet centerline; The first passage further defines an orifice of an outlet section of the valve body having an outlet section centerline; Wherein said outlet section centerline and said inlet centerline are orifices offset in the outlet section such that they are not concentric with the annular seat. The outlet section of the valve body further comprises a trot area having an interior surface defining an orifice with a cross sectional width W _tv , wherein the annular sheet has an inner surface of the seat with a width W _sv . Having an orifice defining a; And the width W _sv is greater than the width W _tv . 12. The valve of claim 11, wherein the orifice of the annular seat and the orifice of the trot area are selected from the group of circular and non-circular geometries. 12. The annular sheet of claim 11, wherein the annular sheet is selected from a group concentric and non-concentric with respect to the orifice of the trot region of the outlet section of the valve body to partially conceal the inner face of the annular sheet from the flow of abrasive particles A valve, characterized in that disposed according to. 14. The arrangement according to claim 13, wherein the arrangement of the inner face of the annular sheet with respect to the orifice of the trot area is further defined by a predetermined distance D _s ; And the distance D _s is within a relation: 0 <D _s ≤ 0.25 (W _tv ). The valve of claim 14, wherein the distance D _s between the inner face of the annular seat and the orifice of the trot region of the outlet section is at least about 400 mils. The valve of claim 14, wherein the valve further comprises an outlet adapter with an orifice having a width W _o . 17. The outlet of claim 16 wherein the outlet of the gate housing further comprises an orifice having an inner wall of a lower face, the height difference H _{Δ being} between the lower face of the inner wall and the inner face of the orifice in the trot region. Limited to the vertical distance of; And the height difference ( _HΔ ) and the outlet adapter width (W _o ) follow the relationship 0 <H _Δ ≤ 0.5 (W _o ). _{18. The} valve of claim 17, wherein the height difference (H _Δ ) and the distance (D _s ) follow the relationship D _{s ≒} 0.25 (H _Δ ). 2. The outlet section of claim 1 wherein the outlet section of the valve body further comprises a trot region having an interior surface, and wherein the second passage of the gate housing is further defined by the interior wall;
The at least one portion selected from the group of the inner face of the trot region in the valve body and the inner wall of the second passage in the gate housing is greater than the hardness indicated by the first region of the valve body or the other region of the second passage of the gate housing. A valve, characterized in that for representing. 20. The valve of claim 19, wherein at least one portion selected from the group of the inner face of the trot region in the valve body and the inner wall of the gate housing exhibits a hardness value greater than about 400 Brinells. 21. The valve of claim 20, wherein at least one portion selected from the group of the inner face of the trot region in the valve body and the inner wall of the gate housing comprises rigid metal carbide grains. 22. The valve of claim 21, wherein the hard metal carbide grains are selected as one from the group of iron carbide, chromium carbide, and mixtures thereof. 22. The valve of claim 21, wherein the hard metal carbide grains are embedded in a matrix having other microstructures, wherein the matrix is softer than the metal carbide grains. The valve of claim 21, wherein the solid metal carbide grains are substantially the same size as abrasive particles. 6. The trot area of claim 5, wherein the trot area in the outlet section of the valve body further comprises a metal or ceramic wear resistant insert; And the insert exhibits a hardness value greater than the hardness indicated by other regions within the outlet section of the valve body. 26. The valve of claim 25, wherein the valve further comprises an access cover having an interior surface that is curved to be generally the same as the interior surface of the valve body defining the first passageway; And the insert is integrally formed with a portion of the access cover. The method of claim 1, wherein the valve is used as part of a particle transport system for collecting and controlling the flow of abrasive particles between a particle collector such as an electrostatic precipitator, a bag house, or an economizer and a processing unit or compound vessel; The particle delivery system is:
At least one hopper for collecting abrasive particles having an inlet and an outlet configured to be in communication with a particle collector for receiving abrasive particles;
And at least one transfer line in communication with the processing unit or compound vessel for transfer of abrasive particles. A method of manufacturing a valve having a valve body, a gate housing, and a gate assembly for opening and closing the valve for controlling the flow of abrasive particles in a particle delivery system, the method comprising:
An inlet section and an outlet section, including an outer cell, a cavity, and an inner core, defining an first passage, the outlet section further defining a first mold of the valve body, defining a trot area having an inner face. Providing;
Filling the cavity of the first mold with molten metal;
Using the inner core of the first mold to cool the molten metal in the mold section representing the inner face of the trot region to cool faster than the remaining molten metal in the cavity;
Removing the casting of the valve body from the first mold;
Providing a second mold of the gate housing having an outer cell, a cavity, and an inner core, the second mold being designed to define a second passageway having an inlet and an outlet with an inner wall;
Filling the cavity of the second mold with molten metal;
Using the inner core of the second mold to cool the molten metal in the mold section representing the lower inner wall to cool faster than the remaining molten metal in the cavity;
Removing the casting of the gate housing from the second mold;
An open position and a closed position, the gate sized to occlude the second passageway of the gate housing and an annular sheet in contact with and engaged with the gate, the annular sheet being valved to partially conceal from the flow of abrasive particles; Providing a gate assembly disposed in size with respect to an orifice established by the outlet section of the body;
Providing an actuator to operate the gate; And
Assembling the valve body, the gate housing, the gate assembly, and the actuator to form a valve;
Rapid cooling resulting from the cooled inner core promotes the formation and growth of hard metal carbide grains; Metal carbide grains reduce the incidence of erosion wear that occurs in contact with the flow of ash particles. 29. The method of claim 28, wherein filling the cavity of the first mold and the cavity of the second mold with molten metal uses iron as the metal. 30. The method of claim 29, wherein filling the cavity of the first mold and the cavity of the second mold with molten iron further comprises adding a predetermined amount of chromium metal dispersed in molten iron to increase the hardness of the valve body against erosion wear. And comprising a step.

Images